1. Field of the Invention
This invention relates to computer file systems. More particularly, the invention relates to a system and method for performing a file system operation on a specified storage tier.
2. Description of the Related Art
Large businesses and other organizations often store a vast amount of computer data of various types, ranging from critical data required to run the business, to emails kept according to regulations, to derived or historical information for trend analysis, etc. A variety of different types of storage devices exist for storing these vast quantities of data, such as various types of optical storage devices, disk drive devices, tape drive devices, etc.
Different types of storage devices have different performance, reliability, and recoverability characteristics. Different types of storage devices can also vary greatly in their cost. High-end storage devices can be more expensive than low-end storage devices by an order of magnitude or even more. As a result, organizations often store different types of data on different types of storage devices. For example, the most important data may be stored on high-end storage devices while less important data is stored on lower-end storage devices.
To accomplish this, the organization may organize storage devices or other storage units into multiple storage tiers, also referred to herein as storage classes. Each storage unit may be assigned to one of the storage tiers. The storage devices or other storage units may be grouped into the storage tiers according to various criteria. For example, in some systems, different storage tiers may represent storage devices having different characteristics, such as I/O performance, cost, reliability, recoverability, data availability, etc. Storage devices with similar characteristics may be assigned to the same storage tier as each other.
As one example, an organization may define three different storage tiers, such as a high-end storage tier, mid-range storage tier, and low-end storage tier. High-end storage devices, such as high-end disk arrays with remote mirroring and frequent point-in-time snapshot capabilities, may be assigned to the high-end storage tier. Mid-range storage devices, such as mid-range disk arrays with less frequent point-in-time snapshots and without remote mirroring, may be assigned to the mid-range storage tier. Low-end storage devices, such as inexpensive disks managed by software or firmware RAID, may be assigned to the low-end storage tier. Different types of data may be stored on storage devices in different storage tiers. For example, the most important data may be stored on storage devices in the high-end storage tier, while the least important data may be stored on storage devices in the low-end storage tier.
The data stored on the various storage devices is typically organized into files managed by one or more file systems. The data may be assigned to different storage tiers at the file level. In other words, each file may be assigned to a storage tier, where different files can be assigned to different storage tiers. Thus, in the example above, the files considered to be most important may be assigned to the high-end storage tier, while the files considered to be least important may be assigned to the low-end storage tier.